Cap for a writing instrument



FIG. 1 is a perspective view according to the present invention;

FIG. 2 is a front elevational view of FIG. 1;

FIG. 3 is a right side elevational view of FIG. 1, the left side being a mirror image of the right side;

FIG. 4 is a rear elevational view of FIG. 1;

FIG. 5 is a top plan view of FIG. 1; and,

FIG. 6 is a bottom plan view of FIG. 1. 

The ornamental design for a cap for a writing instrument, as shown and described. 